Lighting units which are controllable by wireless remote controls are known. Indeed, there is now an increasing demand for wirelessly controllable lighting products. The remote control system can for example be based on RF circuitry, requiring at least a receive antenna and RF receiver circuitry to be built into the lighting unit.
RF wireless transmission circuitry is of course widely used in many different wireless applications such as mobile phones, to send and receive wireless signals. However, there are challenges integrating such circuitry into lighting products.
There are many ways to realize the wireless function, giving different options. The option chosen will depend on the desired design flexibility, performance and cost. For example, an antenna can be wire-based or it can instead be printed on a PCB together with RF and control circuitry.
The performance of the antenna is very important to the overall performance of a wireless controllable lighting product.
A typical LED lighting unit can be separated into different building blocks as schematically shown in FIG. 1. The basic elements include a housing 1, an LED driver circuit board 2, an LED package 4 which may include a circuit board on which the LED die is mounted, and an optical beam shaping component 6. The housing 1 can provide a heat sink function to help dissipate heat out of the lamp. The lighting unit has an electrical connector 7 for connection to an electrical socket.
The beam shaping component optically processes the light output from one or more LEDs. Each LED has typically a 3 mm2 size and is mounted on a ceramic support substrate. The beam shaping component is used to provide a desired output beam shape and also to disguise the point source appearance of the LED. The beam shaping component can be a refracting component (such as a lens) or a reflecting component, such as a reflecting collimator.
The antenna is usually integrated onto the LED driver PCB 2 or the LED board inside the lamp. As a result, the wireless signal is shielded by components of the lamp including the heat sink or housing, which is made from a thermally conductive material, typically a metal such as an aluminium alloy. The exit/receive window for wireless signals is also limited by the PCB dimensions, which are made as small as possible within the lamp. US2002/274208A1 discloses a lamp with a front cover, and the antenna is above its heat sink and is placed on a PCB. US2007/138978A1 discloses a solid state light fixture with an optical processing element for converting solid state source output to virtual source. And US20120026726A1 discloses a lamp with optical element and a wireless control module 2620 above its heat sink.
US 2013/0063317 discloses a method of integrating an antenna, in which the antenna is provided on the surface of a lens.